The Mouse Transgenic Core is designed to provide a centralized service and training facility that will facilitate the generation of transgenic mice for each of the participating investigators. The ability to create transgenic mice that express foreign genes of interest under the control of specific promoters provides a powerful tool to study a range of problems relevant to the research proposals outlined in the current SCOR program. The Mouse Transgenic Core will operate in conjunction with the Transgenic Facility. This latter facility was established at the Beth Israel Deaconess Medical Center in 1991 and is supported by space, equipment, and initial start-up operating funds provided by the Department of Medicine. The Mouse Transgenic Core will provide additional equipment, and ongoing funding for personnel and supplies to accomplish two major aims: to make the facility self supporting by users after its initial start-up and to insure that the needs of the proposed Mouse Transgenic Core can be efficiently met. Responsibilities of the Core will include ordering, maintaining and manipulating the animals required for production of fertilized zygotes or blastocysts, micro injection of cloned DNA or ES cells, embryo transfer into pseudo-pregnant recipients and care of the newborn young. In addition, the Core will provide the time, expertise and supplies necessary for ES cell targeting experiments. The Core will also provide consultation and training in zygote injection to interested investigators. This Core represents a cornerstone of the SCOR Program's goal to pursue new molecular approaches and will serve as a major stimulus to new collaborations among investigators in the area. The objectives of the Core are: (a) to provide a service facility that will utilize investigator-derived DNA constructs and ES cells to create founder transgenic mouse lines that will address relevant questions. (b) To provide training in animal husbandry, colony maintenance and breeding, and transgenic methodologies to researchers who wish to establish programs in this area. (c) To provide consultation to researchers regarding the general aspects of transgenic animal work, the use of tissue specific promoters, the construction of DNA vectors suitable to transgenic work and the availability of transgenic models relevant to their studies.